Bottomless Bowls: Why Visual Cues of Portion Size May Influence Intake^**

TLDR

The study investigated whether visual cues of portion size, delivered through self‑refilling soup bowls, influence intake volume without altering intake estimation or satiety. Fifty‑four participants were randomly assigned to either a normal bowl or a self‑refilling bowl that refilled imperceptibly, and intake volume, estimation, monitoring, and satiety were measured. Participants unknowingly eating from self‑refilling bowls consumed 73% more soup yet reported no difference in perceived intake or satiety, underscoring that visual portion cues drive consumption norms and that accurate visual cues are essential to prevent unintentional overeating.

Abstract

Abstract Objective: Using self‐refilling soup bowls, this study examined whether visual cues related to portion size can influence intake volume without altering either estimated intake or satiation. Research Methods and Procedures: Fifty‐four participants (BMI, 17.3 to 36.0 kg/m 2 ; 18 to 46 years of age) were recruited to participate in a study involving soup. The experiment was a between‐subject design with two visibility levels: 1) an accurate visual cue of a food portion (normal bowl) vs. 2) a biased visual cue (self‐refilling bowl). The soup apparatus was housed in a modified restaurant‐style table in which two of four bowls slowly and imperceptibly refilled as their contents were consumed. Outcomes included intake volume, intake estimation, consumption monitoring, and satiety. Results: Participants who were unknowingly eating from self‐refilling bowls ate more soup [14.7 ± 8.4 vs. 8.5 ± 6.1 oz; F (1,52) = 8.99; p < 0.01] than those eating from normal soup bowls. However, despite consuming 73% more, they did not believe they had consumed more, nor did they perceive themselves as more sated than those eating from normal bowls. This was unaffected by BMI. Discussion: These findings are consistent with the notion that the amount of food on a plate or bowl increases intake because it influences consumption norms and expectations and it lessens one's reliance on self‐monitoring. It seems that people use their eyes to count calories and not their stomachs. The importance of having salient, accurate visual cues can play an important role in the prevention of unintentional overeating.